The present invention relates to a drug delivery device in the form of a hollow guidewire with at least one perforation at the distal end thereof.
Balloon angioplasty is generally an effective method for treating vascular disease, especially atherosclerosis. The build up of plaque in the lumen of a blood vessel, i.e. a stenosis, narrows the lumen and could eventually occlude the lumen if left untreated. Such a situation in a coronary artery can cause a myocardial infarction, i.e., a heart attack. In balloon angioplasty, a balloon located on the distal end of a catheter is used to expand the blood vessel to restore its patency in the area of the stenotic lesion.
Such standard balloon angioplasty procedures, however, may not be suitable when a stenosis substantially occludes the lumen of the blood vessel. If the outer diameter of a deflated balloon dilatation catheter is larger than the void in a blood vessel, the balloon will be unable to cross the lesion to allow the balloon to inflate and restore patency to the blood vessel. A similar problem occurs when a stenosis is located in a very narrow blood vessel which is inaccessible to standard balloon dilatation catheters having outer diameters of about 0.032 to about 0.042 inches (0.081 cm to 0.107 cm) along its distal portion. Occlusions can be alleviated by performing a thrombolytic procedure. Such a procedure is described in "Pharmacologic Adjuncts to Percutaneous Transluminal Coronary Angioplasty," Coronary Balloon Angioplasty, 1994, at pages 231-260: 250,000 IU of urokinase is initially infused over 10 or 20 minutes for native coronary arteries and abrupt closure. For proximal occlusions, a guide-catheter can be used for infusion. An SOS wire or distal lumen of a standard balloon catheter is preferred for more distal occlusions. For distal occlusions with tenuous guidewire position, a Tracker-18 Infusion Catheter (Target Therapeutics, San Jose, Calif.) or a multiple side-hole infusion catheter may be used. Occasionally a further 250,000 IU of urokinase is administered if there is no evidence of any change. After positioning the infusion wire distally into the graft, 50,000 IU/hour of urokinase is infused through both the guide and the infusion catheter. Alternatively, if the guide position is stable, this can be used alone to infuse urokinase into the graft. PTCA of the underlying lesions can be attempted afterwards when thrombus is not visible or when sufficient clearing has occurred to allow flow into the distal native coronary artery.
In some cases, a thrombolytic procedure will only be partially successful, and a thrombus will remain. In other cases, a thrombotic obstruction will be removed revealing an underlying lesion. In such cases, it may be desirable to perform a balloon angioplasty procedure at the site of the remaining thrombus or the site of the underlying lesion.
After a thrombolytic procedure, a stent may be implanted to support the vessel wall. Such stents are used to enlarge and support the lumen, provide a smooth luminal surface, reinforce vessel dissections, tack-up tissue flaps, reduce the risk of plaque rupture, decrease the incidence of complications and reduce the incidence of restenosis. Many different types of stents may be used, such as radially self-expanding stents or balloon-expandable stents. Typically, the stent is placed on the distal end of a wire guided delivery catheter so the stent can be maneuvered adjacent to the treatment site and deployed there. After deployment it may be necessary to expand the stent further with a balloon catheter.
It is therefore an object of the invention to provide a drug delivery device that can cross a very tight occlusion or cross an extremely narrow blood vessel and dispense a drug at a desired site.
It is a further object of the invention to provide a drug delivery device that can be used to deliver a drug to a desired site and then act as a guide wire for an angioplasty balloon catheter, a stent delivery device or other devices for performing intraluminal procedures.